Suppress the DC050001 messages for the DCLOG % full

Products

• IDMS
• IDMS - Database

Issue/Introduction

Is there a way to suppress the DC050001 messages that indicate the DCLOG is  x% full?

Environment

Release: All supported releases.

Resolution

The only way to suppress this message and prevent it from being issued is to modify the route code and destination code in the WTOEXIT.

The frequency with which the DC050001 message is issued depends on how quickly the log fills, and how full the log is when the CV starts up. If the log continues to fill without being offloaded, these messages will indeed appear more frequently. Under normal activity, when the log is not yet close to full, expect to see these roughly whenever another 1/8 (12.5%) of the log area is filled until the log is about 85% full, then with increased frequency. Details follow.

The DC/UCF system monitors the available space in the area, and calculates when the next message should be issued. When the amount of unused space in the area reaches that point, the DC050001 message is issued indicating the percentage of used space in the area. The steps in this procedure are as follows:

1. At startup, IDMS calculates 1/8 (12.5%) of the total number of pages in the log area.
2. The log is checked and the number of pages already in use is rrecorded, and the number of remaining pages is calculated.
3. IDMS calculates 1/2 of the number of remaining pages.
4. If the number of free pages remaining in the log (from step 2) is less than the number calculated in step 1 (1/8 of the total log) then the number calculated in step 3 is used to establish the next message point; otherwise IDMS uses the number from step 1. This value is stored in a field called LWCENT.
5. IDMS calculates the page number in the log area that represents when this calculated percentage will be reached, and stores it in a field called LWPNXT. This is the logical page number for the next DC050001 message.
6. IDMS continues to monitor the available space in the log area.
7. The next DC050001 message is issued when the value in LWPNXT is reached.
8. When the message is issued, IDMS again recalculates to establish the next threshold value for LWCENT & LWPNXT (steps 2 and 5, above). When a log offload is completed, IDMS also recalculate this value.
9. IDMS continues to issue messages from module RHDCMISC whenever a calculated threshold is reached; and continues to reset that threshold whenever the message is issued, or the log is archived.

Additional Information

An example may help to clarify how this works:

1. If the log area contains 4000 pages (page range 22001 to 26000), then 12.5% of the total number of pages in the log area = 500.
2. If the log is empty at startup, then there are 0 pages already in use, 4000 remaining pages.
3. IDMS calculates 1/8 of the 4000 remaining pages = 500 pages.
4. The number of free pages remaining in the log (from step 2) is 4000, which is greater than the value of 500 calculated in step 1 (1/8 of the total log), so IDMS uses 500 to establish the next message point, and store this in LWCENT.
5. Since the log is empty, page number 500 in the area will be page 22501; this is stored in LWPNXT.
6. IDMS continues to monitor the available space in the log area.
7. In the course of this monitoring, when IDMS sees that page 22501 has been filled, calculate how much of the log has actually been filled, and issue a message such as DC050001 V500 T77 DCLOG IS 12% FULL. Depending on how quickly the log is filling up, this may be immediately after that page is filled, or subsequent pages may also have been filled. The percentage will indicate that actual number based on the actual number of pages that were filled when the message is issued.
8. At this point, IDMS again recalculates to establish the next threshold values for LWCENT & LWPNXT, as follows:
1. The log has 500 pages in use, so 3500 pages remain.
2. 1/2 of the 3500 remaining pages = 1750 pages.
3. The number of free pages remaining (3500) is greater than 500, so use 500 to establish the next message point, and store this in LWCENT.
4. Page 22501 + 500 = 23001, so this is stored in LWPNXT.
9. IDMS continues to monitor, and page 23001 has been filled, it issues next log message DC050001 V500 T77 DCLOG IS 25% FULL. IDMS repeats the calculations as above and find that the next value for LWPNXT is 23501.
10. If the log is not offloaded, and continues to fill, IDMS eventually reaches a point where the remaining pages are less than 12.5% of the total number of pages in the area. In this example, that happens if page 25501 fills and IDMS issues DC050001 V500 T77 DCLOG IS 87% FULL. At that point, there are only 499 pages left in the area, so instead of using 500 pages to calculate the next threshold, IDMS uses half of the remaining pages, which is 249. This is added to 25501 and move 25750 to LWPNXT.
11. When page 25750 fills, IDMS issues the message DC050001 V500 T77 DCLOG IS 93% FULL.
12. Since the remaining 250 pages are less than 500, IDMS recalculates a new threshold of 125 pages (half the number of remaining pages), and sets 25875 as LWPNXT.
13. If page 25875 fills, IDMS issues the message DC050001 V500 T77 DCLOG IS 96% FULL.
14. The remaining 125 pages are still less than 500, so IDMS recalculates a new threshold of 67 pages, and sets 25942 as LWPNXT.
15. If page 25942 fills, IDMS issues the message DC050001 V500 T77 DCLOG IS 98% FULL.
16. At whatever point the log is offloaded, a DC050001 V500 T77 DCLOG IS 0% FULL is issued. The LWPNXT is set back to 22501 and the process begins again.

As can be seen in this example, if the log activity follows a consistent pattern, and a log archive is not completed, then the messages will be issued with increasing frequency the closer the log gets to being full (in this example, they will be issued at 12.5%, 25%, ... 87%, 93%, 96%, 98%, 99%, etc). To prevent this, the log area can be made larger; and a WTO exit can be used to initiate a log archive when the percentage indicated in the DC05001 reaches a specified threshold.